1. Field of the Invention
This invention relates to improvements in ophthalmology and more particularly to improvements in the manufacture of artificial intraocular lenses (pseudophakoi) used for the correction of aphakia and re-establishment of binocularity in aphakia.
2. Discussion of the Prior Art
Well-fixed and well-centered intraocular lens implants are known to produce stable retinal images with stable space localization and offer the best chance of re-establishment of binocularity in cases of aphakia.
Many techniques of lens implantation, including suturing to the ciliary muscle as disclosed in U.S. Pat. No. 3,711,870 and iris diaphragm fixation as disclosed in U.S. Pat. No. 3,673,616, for example, have been used. The latter is considered to be a safe procedure giving good stability and the present invention deals with improvements in this general type of pseudophakos. More particularly, the invention relates to improvements in "iridocapsular" and/or "iris clip" implants having a fastening section comprised of posterior and/or anterior haptic elements (iris clips) which may be in the form of loops or struts of wire or wire-like material.
Heretofore, the wires of iris clips have been fastened by extending ends thereof into holes drilled or otherwise formed in the lenses. Anchoring or locking these wires against accidental withdrawal and disconnection from the lens, however, has presented the serious problems of having to establish and maintain exacting tolerances of hole and wire size for fitting, the use and dependence upon adhesives or dealings with intricate and costly special tools and fixtures in attempts to avoid the use of adhesives by press-fitting.
The use of adhesive materials in pseudophakoi not only requires the provision of substances having strong bonding properties but further requires that they be biologically inert and resistant to absorption or deterioration by human body fluids. Under most, if not all, conditions, however, there remains the possibility of deterioration of the bonded components, if not the cement itself, or both, causing loosening or detachment of parts in the eye with prolonged use.
Press-fitting, on the other hand, eliminates the need for adhesives but requires exacting tolerances of hole and wire size which presents exceptional manufacturing problems. The minute size of anchoring hole and wire diameters required of pseudophakoi are alone problematic, not to mention the imposition of press-fitting tolerances. The tediousness of manufacture, its requirement for special jigs, fixtures, tools and skills together with current high scrap yield seriously limit present day output and contribute to high, if not excessive, product cost, all without assurance that loosening or disconnection of parts under usage will not occur. Furthermore, all pseudophakoi require a sturdiness of structure which is sufficient to withstand relatively harsh manipulation and adjustment of parts by the surgeon prior to and/or during implantation. Accordingly, an assurance against accidental disconnection of parts at this point in time as well as subsequent to implantation is of extreme importance and urgently sought in the art.
One solution to the problem of avoiding the use of adhesives and the need for special tolerances of wire fit is disclosed in a co-pending application of the present inventor which was filed on Sept. 22, 1975 and bears Ser. No. 615,275 and is assigned to the assignee of this application. This invention provides beads or similar enlargements upon the ends of pseudophakoi clips which are forced into the material of lenses receiving the same. Locking in situ is accomplished by a cold flow of material around the preformed beads or enlargements.
The present invention, however, is directed toward further simplification of procedure in the manufacture of pseudophakoi which, without the need for adhesives, undue hole and wire size tolerances or beaded wires, uniquely accomplishes an interference fit between lens and iris clips which provides a positive and dependable locking together of these parts. A further aim of the invention is to accomplish the foregoing objective with greater than usual ease and substantially less than usual product cost.